GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) capable of handling raster, topological vector, image processing, and graphic data.

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9
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412 views

SEXTANTE toolbox - GRASS error

I am trying to use the SEXTANTE module GRASS (and SAGA) for vector analysis but whatever function I use I always get the same error:"Could not load layer: G:/closest.shp Check the SEXTANTE log to look ...
7
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653 views

GRASS v.Overlay/QGIS Intersect Speed intersecting line and polygon

Im currently trying to convert my scripts from ArcGIS to QGIS but one aspect that is extremely slow (imo) is trying to intersect a polygon with a line feature. I feel as though there must be a better ...
4
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197 views

How to create a topologically correct dataset in PostGIS (with GRASS)?

I have shapefiles which I have loaded in postgis and now i am trying to use geometric function in postgis like ST_intersect and they fail because the data is not topological correct. I have tried to ...
2
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0answers
45 views

Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
2
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49 views

Background (sky/terrain) of a viewshed

Is it possible to determine whether a point feature of a particular height would be backed by sky or by terrain? I've done the viewsheed analysis of a wind turbine. Now I would like to make a raster ...
2
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0answers
128 views

Snap points to line and calculate chainage using Open source GIS

I have a line layer (representing a pipeline) and a points layer (representing valves) and I would like to calculate the chainage of the valves along the pipeline. I assume that I would first need ...
2
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33 views

QGIS V. parallel command using GRASS

I cannot offset a line to a specific decimal place, (ie only whole numbers can be inputted) Am I missing something here??
2
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0answers
63 views

Longest slope oriented to north?

I need a help with my homework. I have created digital elevation model from the shapefile. In QGis(Grass plugin) This is how far i can go. I have to find the longest slope oriented to North. I know ...
2
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0answers
184 views

how to make decent sense from scattered river depth measurements

I sampled river depth at scattered positions and I want to be able to make a map and GIS layers out of it. My problems are: As the river meanders the interpolation I do in scientific packages i,e. ...
2
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146 views

How can I create random concave polygons for test purposes?

In the context of generating random test data using QGIS (in a shapefile): I can generate random, continuous (adjacent) polygons by first creating n random points using ftools and then generating a ...
2
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0answers
179 views

How to Install GRASS Addons to use in QGIS

WIN 7 QGIS 1.8.0 GRASS 6.3.4 I want to use r.viewshed in QGIS. therefore i want to install it in GRASS by using the GRASS interface. Followin Error appears. g.extension.py extension=r.viewshed ...
2
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195 views

Solar irradiation calculation using r.sun

I am trying to compute the global solar irradiation for a region and the run times seem to be a bit too high. I have as inputs a Digital Surface Model with the buildings and a Digital Terrain Model ...
2
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282 views

How to specify cost attributes for network analysis in QGIS using the GRASS plugin?

I have a road dataset with information about the length, speed and drivetime for each segment. I use QGIS 1.9 with the GRASS plugin to do different types of network analysis, but how do I set up the ...
2
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0answers
86 views

How to create the fuel models & live fuel moisture rasters for Wildfire simulation?

Has anybody done wildfire modelling in GRASS? Where could I obtain / how do I create the fuel models and live fuel moisture rasters to determine rate of spread (r.ros)?
2
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0answers
26 views

How to remove coastlines from Admin 0 data set using GRASS?

I have a set of international borders that I would like to overlay on top of a different data layer that represents coastlines ("land" essentially). I would like to convert my Admin 0 polygons into ...
2
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0answers
390 views

GRASS GIS - r.water.outlet - What is my mistake?

I'm new to GIS - more so in GRASS GIS. I installed GRASS GIS 6.4.3svn in my Windows 7 machine. No problem in installation. Downloaded SRTM-Geotiff file Location, Mapset all o.k Used r.in.gdal to ...
2
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0answers
861 views

Simulate flood to assess Asset inundation footprints

I am trying to evaluate a number of flood gauges to assess at what levels of river height different flood risks would need to be issued. The gauges are currently set to warn of flood a couple of ...
2
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0answers
117 views

How to fix Graphserver warning “osmdb has no edges!”?

I'm really new to GIS. I have some shapefiles data that I'm trying to import in graphserver. I'm doing: gs_osmdb_compile output3.osm output3.osmdb And the result is: WARNING: osmdb has no edges!. ...
1
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14 views

Problem with Command Console (GRASS GIS 7.0,0 beta2 on Windows 8.1)

I have a problem with Command Console. When I do for example, File-> Map display-> Add raster-> elevation, it works. But when I write into Command Console d.rast map=elevation@PERMANENT, it ...
1
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0answers
14 views

GRASS and r.viewshed

I'm trying to run the r.viewshed command using co-ordinates held in a .csv file I imported using v.in.ascii. It has over 200 rows and I'm looking to run viewsheds from each line, without doing it ...
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0answers
91 views

QGIS 2.2.0 GRASS not worked

I use QGIS 2.2.0 on Windows 8 64 bit. I try to install use Standalone installer and OSGeo4W and still get the error And then i start GRASS C:\Program Files (x86)\GRASS 6.4.2>grass64 ╬╪╚┴╩└: ...
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41 views

Error “Unable to open data source” - import .shp into GRASS

I'm new to GRASS and GIS in general, so please forgive my ignorance... I have problem with loading Vector Data (.shp) into GRASS I used the following steps 1.1. and 1.2: ...
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21 views

Extrude polygons with holes in GRASS using v.extrude

I have a shapefile with building footprint polygons. Many of the polygons have holes/inner rings within them (I'm not sure of the correct term in Grass). These import correctly into Grass GIS. I aim ...
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24 views

Fill holes with an area bigger of a specific value in a raster coverage

I want to fill some areas of a raster coverage with a value of my choice. Those areas now contain NODATA values. So, they look like holes in my coverage. I know I could use r.clump function of GRASS, ...
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35 views

Is there any GRASS command to measure the distance between a point in rastermap and another in vector map?

I have a question about WinGRASS 6.4.3. Is there any GRASS script command to measure the distance between a point in rastermap and another in vector map? I have a raster map and a vector map. Raster ...
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0answers
35 views

“System not initialized. Programmer forgot to call G_gisinit().” message when loading table into GRASS via QGis

I am trying to load a CSV table into Grass with v.in.asciifrom the interface of Qgis 2.0.1 on Windows XP. As the progress bar indicated 74% of the data already loaded, I got the message "System not ...
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0answers
25 views

Multiply vector categories

I have imported a Vector map into GRASS GIS. There are some problems with the topology and some polygon areas overlap. I used v.clean to break overlapping polygons and now I have multiple polygons ...
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49 views

header information is missing from image, after writing using opencv

I am doing complement of an image using open-cv python, while writing the image, open-cv is not writing the header information in the complemented image. my image data are in TIFF format. i am doing ...
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94 views

Merging contour lines along tile boundaries

I am working with the CANVEC data set. The data in canvec is broken up in to mapsheets. eg. 116B04. I have data covering the entire province of the Yukon. I have merged all the data in to one ...
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0answers
80 views

Touch up tool for rasters?

I was wondering if it were at all possible to manipulate/massage rasters (eg Geotiff) using Qgis plugins or Grass?? By manipulate, I mean manually smooth off interpolation artefacts, blended surface ...
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43 views

Communicate synchronously & continuously (coords, etc) from terminal to application-based mapping software such that updates are displayed live on map

I run a lot of spatial queries. Hundreds of thousands a week. While these things are running, it would be nice if I could see what (where, actually) my scripts are working with. Distance calculations, ...
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0answers
50 views

Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
1
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0answers
20 views

Unicode Characters in GRASS ps.map instructions file

I am trying to put text on a ps.map generated map and the text contains the degrees symbol. I can insert the symbol into the instructions file, and it looks fine, but when I generate the map, the ...
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0answers
148 views

Problems with SEXTANTE

maybe the answer is somewhere, but i can't find it right now... I'm getting problems with SEXTANTE and algorithms with GRASS, SAGA... Always is the same, they can't open the files, the error is the ...
1
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0answers
99 views

where to perform principal components analysis and tasseled cap transformation

I want to perform a principal components analysis (pca) and a tasseled cap transformation (tasscap) for a classification.Should i perform pca and tasscap on the original bands of my image or on the ...
1
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0answers
49 views

grass region resolution error

I am working on a raster, but I can't set a correct region for it. In the Set region to match this raster map field, I select my raster map to change current region, but its resolution does not ...
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0answers
76 views

Getting an error when I try to import a loaded vector file to the QGIS GRASS Plugin

I am getting an error code when I try to import a contour line vector file GRASS via QGIS. I have been trying to create a DEM from the contour lines following this tutorial: ...
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0answers
84 views

How to Configure sextante in Qgis 1.9 ubuntu

I am using Ubuntu 13.04 and the most up to date version of Qgis 2.1.0-Master. I am trying to get sextante to work correctly and have a hard time. Specifically SAGA 2.1.0 and GRASS 6.4.2 will not ...
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0answers
672 views

How do I change from lat/long to a metric coordinate system in GRASS?

Yes, it's yet another transformation question. I am working with ASTER DEM data, which is LatLong WGS84. I want to process the DEM map into an STL file for use in a CFD simulation. The script I am ...
1
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0answers
58 views

GRASS GIS SDTS Manipulation

Preface: I'm a total GIS noob. Flame away. I'm learning GIS in my free-time and with free resources. I realize that is likely going to force me on the learn-fast-or-giveup track, but here it goes... ...
1
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0answers
99 views

GRASS v.overlay.or Error when trying to split a polygon with a line

I am using the Grass plugin in QGIS for Windows (1.8.0). I am trying to split a polygon with a line feature. I am using the v.overlay.or function within the QGIS Grass plugin. I have the line layer ...
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0answers
324 views

GRASS Plugin to QGIS error

I am installing QGIS and GRASS as part of an FOSS GIS class I'll be teaching this summer. I used the OsGeo4W installer. This installer has always worked flawlessly for me except on the machines at the ...
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0answers
156 views

Heat Map trouble: Is this a data formating problem?

I'm playing with the heat map plugin with QGIS. I've run through QGIS tutorial: http://docs.qgis.org/html/en/docs/user_manual/plugins/plugins_heatmap.html, using the airports data set as explained ...
1
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0answers
97 views

GRASS python script runs twice

Is there a reason that every script I have written for GRASS in python runs twice? I start them using the GUI script launcher tool, and they all begin with: #!/usr/bin/python import grass.script as ...
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213 views

How to handle/ avoid intersect errors when clipping the difference between two layers?

Using QGIS + Grass, I've added a shapefile of coastline and islands to my map. I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
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0answers
134 views

i.maxlik cannot read i.class output signature file

I'm trying to perform a supervised classification using i.class. I'm then using i.maxlik, but this is returning the following error: GRASS 6.4.3svn (India_01):~ > i.maxlik group=test_group@test ...
0
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0answers
15 views

Execute Spyder within Grass GIS

I'm using GRASS Gis with a small Python script. Is there a way (for windows users) to use the sypder ide within grass? I looked at http://grasswiki.osgeo.org/wiki/Tools_for_Python_programming but ...
0
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0answers
13 views

v.clean in QGIS Python console

I have tried to use v.clean and v.clean.advanced (by GRASS GIS) within a script in QGIS, and was not able. I followed instructions here:, but was not able to do so. I got message: "No module named ...
0
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0answers
27 views

Does somebody has a Python script for a Multiple Flow Algorithm?

I´m looking for for a python script for a multiple flow algorithm assigning flow to all lower cells from one central cell. This algorithm is part of the r.terraflow and would need it to start at a ...
0
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0answers
17 views

GRASS r.out.mat memory issues

we have built a model with pythn/GRASS that calls the r.out.mat module. The area is quite large 25,000x25,000 cells. The machine we are running it on is Windows 7 machine with 16GB of RAM. After a ...